In Step 1, all participants will receive VPA while continuing their current HAART. Doses of VPA will vary by participant. Study visits will occur on Days 0 and 3 and Weeks 1, 2, 4, 8, 12, 16, and 24. A physical exam and blood and urine collection will occur at most visits. Leukapheresis and genital secretion collection will occur at study entry and Weeks 12 and 16. After 24 weeks, participants will enter Step 2. Those participants not responding to VPA in Step 1 will enroll in Step 2A. Participants responding to VPA in Step 1 will enroll in Step 2B.